Biomolecules

i. Preparation of Glucose from Sucrose: Sucrose ( ) is hydrolyzed in the presence of dilute acid (e.g., HCl) or enzyme (invertase) to produce glucose and fructose: ii. Structure of D-Ribose: D-Ribose is a pentose sugar with the following open-chain structure: In its cyclic form (furanose), it is:

Part 1: Peptide Bond and its Formation
A peptide bond is a covalent chemical bond formed between two amino acid molecules. It is an amide-type bond (-CO-NH-). Formation: It is formed when the carboxyl group (-COOH) of one amino acid reacts with the amino group (-NH ) of another amino acid. This is a condensation (or dehydration) reaction, where a molecule of water is eliminated. The resulting molecule is a dipeptide.
Part 2: Reagent for Alkyl Halide to Nitroalkane Conversion
To convert an alkyl halide to a nitroalkane, the reagent used is silver nitrite.
- Name: Silver Nitrite
- Formula: AgNO
The reaction is:

Glucose can be prepared in the laboratory by the hydrolysis of sucrose (cane sugar). Procedure: Sucrose is boiled with a dilute solution of a mineral acid, such as hydrochloric acid (HCl) or sulfuric acid (H SO ), for about two hours. The acid acts as a catalyst for the hydrolysis reaction.
Reaction: During this process, one molecule of sucrose breaks down to give one molecule of glucose and one molecule of fructose.
The resulting solution contains an equimolar mixture of glucose and fructose. Glucose is less soluble in ethanol than fructose, so adding ethanol to the cooled solution causes glucose to crystallize out, while fructose remains dissolved.

Step 1: Understanding the Concept:
Bromine water ( ) is a mild oxidizing agent. It specifically oxidizes the aldehyde group ( ) of glucose without affecting the hydroxyl groups.
Step 2: Detailed Explanation:
Glucose contains one aldehyde group and five hydroxyl groups. When treated with bromine water, the aldehyde group is oxidized to a carboxylic acid group ( ).
The product formed is gluconic acid.
Reaction:

This reaction confirms the presence of an aldehyde group in the open-chain structure of glucose.
Step 3: Final Answer:
Glucose reacts with bromine water to form gluconic acid.

Step 1: Understanding the Concept:
Starch is a polysaccharide. Hydrolysis breaks the glycosidic bonds to yield its monomeric units (glucose).
Step 2: Detailed Explanation:
Commercially, glucose is prepared by boiling starch with dilute sulfuric acid ( ) at 393 K under 2 to 3 atmospheres of pressure.
Reaction:

After hydrolysis, excess acid is neutralized with chalk ( ), and the glucose is crystallized from the concentrated solution.
Step 3: Final Answer:
Glucose is produced by boiling starch with dilute at 393 K and 2-3 atm pressure.

Step 1: Understanding the Concept:
Proteins are polymers made of amino acids. The linkage that joins these amino acids together is the peptide bond or peptide linkage.
Step 2: Detailed Explanation:
A peptide linkage is an amide bond ( ) formed by the condensation reaction between the carboxyl group ( ) of one amino acid and the amino group ( ) of another amino acid, with the elimination of a water molecule.

Step 3: Final Answer:
The peptide linkage is the covalent bond connecting amino acids in a polypeptide chain.

Concept:
Vitamins are essential organic compounds required in small amounts for normal body metabolism. Each vitamin has a common name and a chemical name.
Vitamin :

Chemical name:
Riboflavin

Water-soluble vitamin
Belongs to the Vitamin B-complex group
Functions:

Helps in energy production
Important for skin and eye health
Plays a role in cellular respiration
Sources:

Milk and dairy products
Eggs
Green vegetables
Whole grains

Concept:
Proteins are complex biomolecules made up of long chains of amino acids linked by peptide bonds. When proteins are broken down chemically, these peptide bonds are cleaved.
Explanation:

Hydrolysis involves breaking bonds using water (acidic, basic, or enzymatic conditions).
During hydrolysis, peptide bonds in proteins are broken.
This releases individual amino acid units.
Reaction Representation:

Conclusion:
Since proteins are polymers of amino acids, their complete hydrolysis yields amino acids.